Cadmus, a prince of Tyre, travelled to the Delphic Oracle after his sister was stolen away by Zeus, chief of the Greek gods. There he was told that, instead of searching for his sister, he should ‘follow the cow outside and wherever it rests, build a new city’.

When the cow stopped Cadmus’s followers went in search of water. A dragon was guarding the spring they found; it slaughtered them all. Cadmus